From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2345ECAAD2 for ; Mon, 29 Aug 2022 11:30:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232340AbiH2LaR (ORCPT ); Mon, 29 Aug 2022 07:30:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47338 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232680AbiH2L3g (ORCPT ); Mon, 29 Aug 2022 07:29:36 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C9BDA7B1FE; Mon, 29 Aug 2022 04:17:59 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id AC14361265; Mon, 29 Aug 2022 11:17:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A4C08C433D6; Mon, 29 Aug 2022 11:17:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661771833; bh=4vyBfHJMqDH0kiRRLnL90LgZzWk1Zt/AhZzOVdGozek=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0dkmZ5tOno9PlQspIXEFT8byOP2Ty5pZX0t7NhQX0MjMgS977GQgPJaFWXK+nZZJH cM/csUcsfVmbvmINulRHS5UIHoMOQ6tL6UCLKyMYDbnF64CP7+fedli5UWnhIMjFg9 laoIWaCoVdnHYFiB3iR8DINc7d90P42j+BSZ2sYQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Khazhismel Kumykov , Jan Kara , Michael Stapelberg , Wu Fengguang , Alexander Viro , Andrew Morton Subject: [PATCH 5.19 111/158] writeback: avoid use-after-free after removing device Date: Mon, 29 Aug 2022 12:59:21 +0200 Message-Id: <20220829105813.761083165@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220829105808.828227973@linuxfoundation.org> References: <20220829105808.828227973@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Khazhismel Kumykov commit f87904c075515f3e1d8f4a7115869d3b914674fd upstream. When a disk is removed, bdi_unregister gets called to stop further writeback and wait for associated delayed work to complete. However, wb_inode_writeback_end() may schedule bandwidth estimation dwork after this has completed, which can result in the timer attempting to access the just freed bdi_writeback. Fix this by checking if the bdi_writeback is alive, similar to when scheduling writeback work. Since this requires wb->work_lock, and wb_inode_writeback_end() may get called from interrupt, switch wb->work_lock to an irqsafe lock. Link: https://lkml.kernel.org/r/20220801155034.3772543-1-khazhy@google.com Fixes: 45a2966fd641 ("writeback: fix bandwidth estimate for spiky workload") Signed-off-by: Khazhismel Kumykov Reviewed-by: Jan Kara Cc: Michael Stapelberg Cc: Wu Fengguang Cc: Alexander Viro Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- fs/fs-writeback.c | 12 ++++++------ mm/backing-dev.c | 10 +++++----- mm/page-writeback.c | 6 +++++- 3 files changed, 16 insertions(+), 12 deletions(-) --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -134,10 +134,10 @@ static bool inode_io_list_move_locked(st static void wb_wakeup(struct bdi_writeback *wb) { - spin_lock_bh(&wb->work_lock); + spin_lock_irq(&wb->work_lock); if (test_bit(WB_registered, &wb->state)) mod_delayed_work(bdi_wq, &wb->dwork, 0); - spin_unlock_bh(&wb->work_lock); + spin_unlock_irq(&wb->work_lock); } static void finish_writeback_work(struct bdi_writeback *wb, @@ -164,7 +164,7 @@ static void wb_queue_work(struct bdi_wri if (work->done) atomic_inc(&work->done->cnt); - spin_lock_bh(&wb->work_lock); + spin_lock_irq(&wb->work_lock); if (test_bit(WB_registered, &wb->state)) { list_add_tail(&work->list, &wb->work_list); @@ -172,7 +172,7 @@ static void wb_queue_work(struct bdi_wri } else finish_writeback_work(wb, work); - spin_unlock_bh(&wb->work_lock); + spin_unlock_irq(&wb->work_lock); } /** @@ -2082,13 +2082,13 @@ static struct wb_writeback_work *get_nex { struct wb_writeback_work *work = NULL; - spin_lock_bh(&wb->work_lock); + spin_lock_irq(&wb->work_lock); if (!list_empty(&wb->work_list)) { work = list_entry(wb->work_list.next, struct wb_writeback_work, list); list_del_init(&work->list); } - spin_unlock_bh(&wb->work_lock); + spin_unlock_irq(&wb->work_lock); return work; } --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -260,10 +260,10 @@ void wb_wakeup_delayed(struct bdi_writeb unsigned long timeout; timeout = msecs_to_jiffies(dirty_writeback_interval * 10); - spin_lock_bh(&wb->work_lock); + spin_lock_irq(&wb->work_lock); if (test_bit(WB_registered, &wb->state)) queue_delayed_work(bdi_wq, &wb->dwork, timeout); - spin_unlock_bh(&wb->work_lock); + spin_unlock_irq(&wb->work_lock); } static void wb_update_bandwidth_workfn(struct work_struct *work) @@ -334,12 +334,12 @@ static void cgwb_remove_from_bdi_list(st static void wb_shutdown(struct bdi_writeback *wb) { /* Make sure nobody queues further work */ - spin_lock_bh(&wb->work_lock); + spin_lock_irq(&wb->work_lock); if (!test_and_clear_bit(WB_registered, &wb->state)) { - spin_unlock_bh(&wb->work_lock); + spin_unlock_irq(&wb->work_lock); return; } - spin_unlock_bh(&wb->work_lock); + spin_unlock_irq(&wb->work_lock); cgwb_remove_from_bdi_list(wb); /* --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2867,6 +2867,7 @@ static void wb_inode_writeback_start(str static void wb_inode_writeback_end(struct bdi_writeback *wb) { + unsigned long flags; atomic_dec(&wb->writeback_inodes); /* * Make sure estimate of writeback throughput gets updated after @@ -2875,7 +2876,10 @@ static void wb_inode_writeback_end(struc * that if multiple inodes end writeback at a similar time, they get * batched into one bandwidth update. */ - queue_delayed_work(bdi_wq, &wb->bw_dwork, BANDWIDTH_INTERVAL); + spin_lock_irqsave(&wb->work_lock, flags); + if (test_bit(WB_registered, &wb->state)) + queue_delayed_work(bdi_wq, &wb->bw_dwork, BANDWIDTH_INTERVAL); + spin_unlock_irqrestore(&wb->work_lock, flags); } bool __folio_end_writeback(struct folio *folio)